If I am understanding you correctly you want one of the arguments to be a player?
Ways for ULX
For a player:
YOURCOMMAND:addParam{ type=ULib.cmds.PlayerArg }
For an IP, you need to add this:
YOURCOMMAND:addParam{ type=ULib.cmds.StringArg }
For either of those you could also add a hint, for instance, psay:addParam{ type=ULib.cmds.PlayerArg, hint="player" }