The client_id is the same in all functions, it is the unique ID that identifies a client and has to be used in all functions. There is a function to get the client_id by sys_userid of a record. All functions are described in detail in the new api docs.
furthermore there are no $params description. Have you a manual or something that can help me?
There is a full params description in the api documentation and also a working example function for each api call. Download the 3.0.4 beta and take a look in the remote_client folder or get the latest svn release.