diff --git a/README.md b/README.md
index b2b91e2..38ee21b 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,8 @@
 [![Unit-Tests](https://github.com/gookit/greq/workflows/Unit-Tests/badge.svg)](https://github.com/gookit/greq/actions)
 [![Coverage Status](https://coveralls.io/repos/github/gookit/greq/badge.svg?branch=main)](https://coveralls.io/github/gookit/greq?branch=main)
 
+> [中文说明](README.zh-CN.md) | [English](README.md)
+
 **greq** A simple http client request builder and sender
 
 ## Features
diff --git a/README.zh-CN.md b/README.zh-CN.md
index 2ce7580..680d648 100644
--- a/README.zh-CN.md
+++ b/README.zh-CN.md
@@ -7,6 +7,8 @@
 [![Unit-Tests](https://github.com/gookit/greq/workflows/Unit-Tests/badge.svg)](https://github.com/gookit/greq/actions)
 [![Coverage Status](https://coveralls.io/repos/github/gookit/greq/badge.svg?branch=main)](https://coveralls.io/github/gookit/greq?branch=main)
 
+> [中文说明](README.zh-CN.md) | [English](README.md)
+
 **greq** A simple http client request builder and sender
 
 ## 功能说明
diff --git a/builder.go b/builder.go
index e4a4ee7..7bdb9ae 100644
--- a/builder.go
+++ b/builder.go
@@ -45,8 +45,8 @@ func NewBuilder(fns ...OptionFn) *Builder {
 }
 
 // BuilderWithClient create a new builder with client
-func BuilderWithClient(c *Client) *Builder {
-	return NewBuilder().WithClient(c)
+func BuilderWithClient(c *Client, optFns ...OptionFn) *Builder {
+	return NewBuilder(optFns...).WithClient(c)
 }
 
 func newBuilder(c *Client, method, pathURL string) *Builder {
@@ -104,9 +104,7 @@ func (b *Builder) AddQuery(key string, value any) *Builder {
 // The value will be encoded as url Query parameters on send requests (see Send()).
 func (b *Builder) QueryParams(ps any) *Builder {
 	if ps != nil {
-		queryValues := httpreq.ToQueryValues(ps)
-
-		for key, values := range queryValues {
+		for key, values := range httpreq.ToQueryValues(ps) {
 			for _, value := range values {
 				b.Query.Add(key, value)
 			}
@@ -122,6 +120,11 @@ func (b *Builder) QueryValues(values gourl.Values) *Builder {
 	return b.QueryParams(values)
 }
 
+// WithQuerySMap appends map[string]string to the Query string.
+func (b *Builder) WithQuerySMap(smp map[string]string) *Builder {
+	return b.QueryParams(smp)
+}
+
 //
 //
 // ----------- HeaderM ------------
diff --git a/client.go b/client.go
index a8eef33..f5c370c 100644
--- a/client.go
+++ b/client.go
@@ -7,7 +7,6 @@ import (
 	gourl "net/url"
 	"strings"
 
-	"github.com/gookit/goutil/basefn"
 	"github.com/gookit/goutil/netutil/httpctype"
 	"github.com/gookit/goutil/netutil/httpheader"
 	"github.com/gookit/goutil/netutil/httpreq"
@@ -218,6 +217,11 @@ func (h *Client) DefaultMethod(method string) *Client {
 	return h
 }
 
+// Builder create a new builder with current client.
+func (h *Client) Builder(optFns ...OptionFn) *Builder {
+	return BuilderWithClient(h, optFns...)
+}
+
 //
 // ------------ REST requests ------------
 //
@@ -229,9 +233,8 @@ func (h *Client) Head(pathURL string) *Builder {
 
 // HeadDo sets the method to HEAD and request the pathURL,
 // then send request and return response.
-func (h *Client) HeadDo(pathURL string, withOpt ...*Options) (*Response, error) {
-	opt := basefn.FirstOr(withOpt, &Options{})
-	return h.SendWithOpt(pathURL, opt.WithMethod(http.MethodHead))
+func (h *Client) HeadDo(pathURL string, optFns ...OptionFn) (*Response, error) {
+	return h.SendWithOpt(pathURL, NewOpt2(optFns, http.MethodHead))
 }
 
 // Get sets the method to GET and sets the given pathURL
@@ -291,6 +294,11 @@ func (h *Client) DeleteDo(pathURL string, optFns ...OptionFn) (*Response, error)
 
 // ----------- URL, Query params ------------
 
+// WithContentType with custom Content-Type header
+func (h *Client) WithContentType(value string) *Builder {
+	return BuilderWithClient(h).WithContentType(value)
+}
+
 // JSONType with json Content-Type header
 func (h *Client) JSONType() *Builder {
 	return BuilderWithClient(h).JSONType()
@@ -350,9 +358,7 @@ func (h *Client) BodyReader(r io.Reader) *Builder {
 
 // BodyProvider with custom body provider
 func (h *Client) BodyProvider(bp BodyProvider) *Builder {
-	b := BuilderWithClient(h)
-	b.Provider = bp
-	return b
+	return BuilderWithClient(h).BodyProvider(bp)
 }
 
 // ----------- Do send request ------------
diff --git a/option.go b/option.go
index 8996712..49902f3 100644
--- a/option.go
+++ b/option.go
@@ -96,14 +96,29 @@ func ensureOpt(opt *Options) *Options {
 	return opt
 }
 
+//
+// ----------- built in OptionFn ------------
+//
+
 // WithMethod set method
-func (opt *Options) WithMethod(method string) *Options {
-	if method != "" {
-		opt.Method = method
+func WithMethod(method string) OptionFn {
+	return func(opt *Options) {
+		if method != "" {
+			opt.Method = method
+		}
 	}
-	return opt
 }
 
-//
-// ----------- Build Request ------------
-//
+// WithContentType set content-type
+func WithContentType(contentType string) OptionFn {
+	return func(opt *Options) {
+		opt.ContentType = contentType
+	}
+}
+
+// WithUserAgent set user-agent header
+func WithUserAgent(userAgent string) OptionFn {
+	return func(opt *Options) {
+		opt.Header.Set("User-Agent", userAgent)
+	}
+}