It's possible to quickly convert a Job list to a Client list. This can be useful if you need to view other information about the clients in the Job list, or if you wanted to send them a bulk email.
Open your Jobs list (Work > All Jobs)
Apply any filters to the list you need, such as Job filters and status filters
Select all of the Jobs shown in the list
Choose View as client list from the 'Actions' menu
You will then be shown a Client list with the appropriate clients