To deploy an effective client-server environment, once you establish a server, the clients need to be configured to access the server and all the services it provides. This means connecting to the printers, shared file resources, databases, and whatever else has been installaed on the server and designated for client use.
But this just makes use of the obvious benefits of having a server at the ready. To do justice to the client-server concept, you should organize and increase your security as well. User-level access should be controlled to allow only authorized users onto any client computer. These access levels should also extend to the individual server resources available through the client.
For large or complex situations, establishing a domain and a domain controller will simplify management of users and computers. A domain is a defined set of networked computers that all belong to the same group and have some administrative tasks performed by one central computer - the domain controller.