WOW!!! Netware 3.11 still in use today?
I don't think you need a specific client, but netware 3.11 didn't yet use TCP/IP, but rather it's IPX protocol, so you'd have to find IPX to install on Vista. The link below seems to have this for vista32 bit, but it looks like there is nothing for vista64:
http://en.kioskea.net/telecharger/telecharger-3890-support-ipx-for-vista