You can't access arbitrary variables (e.g. clientr) of another player on clientside. That would require an enormous amount of data to be constantly synced to every player on the server (or at least in the same level).
Without knowing what your end goal is (would it make sense to do this stuff serverside?), you can always store the data you need in players' "attr" arrays. Those are accessible by other players in the same level (globally if you configure it in server options), although there are restrictions on the amount and format of data you can store.
If you want to ask the server explicitly for the data, you can use triggerServer, but instead of using "return" to send back data, you use triggerClient. There are some examples [here](
http://forums.graalonline.com/forums...17&postcount=4).