|client server network in workgroup|
That is what you call an oxymoron. It can be a client/server network or it can be a workgroup network, not both. You have no control at all over any other computer in a Workgroup network unless you are actually sitting down in front of it and there is no way you can change that. If you want centralised control you are going to have to invest in a server operating system.
Windows server operating systems are more expensive than desktop operating systems and they come with a license for a set number of users, minimum five. If you want more users you buy more licenses.