You'd have to understand exactly what the server<->client communication looks like. The server and client are independent programs, so in general (from a naive perspective) it doesn't matter if they are made with different programming languages. Circumstances, though, such as custom encryption, encoding, or systems that otherwise manipulate the packets to/from the server may be easier to do in a specific language simply because the code is already done in the server. In general, it's easier to do the client and server in the same programming language, but most of the time the server and client are in different programming languages.
So to answer the "if", yes you certainly can. To answer the "how", you would need a strong foundation on network programming. Are you trying to take an existing client designed for a different server, and just plug it into your server? I've got more questions than answers here, so I can't really answer this.