Taking someone elses client.cs and trying to attach it to the source you're using would most likely lead to a source that won't build. The best you can do is study their .cs file, and toss some pieces onto yours, but even then, they may require portions of coding in other .cs files, so all in all, a complete waste of time.
Edit: Even having a the same source as someone else means nothing if they don't contain all the same portions of info.