Networking. Client request data?

Hello,

Is it possible to have a client request data from the server which is then only sent to that client? I have a large array of points that is prone to change in game that are only relevant to certain clients at certain times of the game. Rather than replicate the array across (which is rather big) as it would work out a lot more efficient. especially since the array will never be required on all clients.

Initially i used a multicast which works but of course it sends the data back to all of the clients which i really want to avoid.

Any help would be appreciated.

Thanks!

Rengee