Drafts work a little like your email and save locally, i would suggest you use the request status and queue, subject to how you work
Maybe use the status of new as your thinking of draft, allow them to submit and work on the request adding info or even docs and assets then..
..Add a new status of Ready to Brief (or what ever works for you) and use this status to make it visible to the team who would currently see as status of New. By altering your filters to remove any briefs with the status of new. The requester could see New (Draft) via requests i submitted or you can build a report that shows them. And your current user see when switched to ready to brief and continues on your current workflow.
This logic works in boards or Kanban as well. It also means you can see and report on the number you have in New (draft).
