Automated Company Document Creation

I hope the follwoing isnt to much to ask, but could some please help me solve the follwing problem I have.

I have a list of +150 Documents, various nature. All with repeating data, CLIENTNAME, CLIENTADDRESS, ect.

I want my Team Members to choose a document from the libary and than choose a Client Name from a sharepoint list to than populate this document with all the Client Data that the document requires.

Or the reverse is fine as well, click client Name and than choose one of the +150 Documents to be created.

Can someone guide me in a direction on where to start to build something like that?

Thank you