C# WebClient non-english request header value encoding

问题

I want to add some custom headers into web request's header. I'm doing this by WebClient.Headers.Add("Header: Value") approach. There is not a problem with ASCII characters but non-ASCII characters.

Is it possible to change "Value of Header's encoding"?

来源：https://stackoverflow.com/questions/14751072/c-sharp-webclient-non-english-request-header-value-encoding