I am looking for a chat app which has support for multiple clients on Android platform.
Why not try the popular Yahoo! Messenger for Android? It now supports audio and video calls.
You can also try Palringo
Yeah - Meebo's awesome. If you want a few others to try out, give Trillian for Android a shot, as well as eBuddy (although I've heard eBuddy crashes on some units). Personally I get by with gTalk - anyone who wants to get in touch with me via mobile has to have a gTalk account or it's not happening. :)
Good luck - hope you find one that works well for you!
Check out Meebo. It should be able to do everything you're looking for.