There are several ways this can be done. If we take the example of sales order search where we narrow based on sales rep. You can for example create a critera "Sales rep any of -mine-" which will dynamically set the criteria.
if we're talking a little bit more advanced searches you can use Formulas and the fields {user} and {userrole}. which gives ID:s of the user and the users role when they run the search
Edit: Might have misunderstood you, could you elaborate on "populate the record"? Do you mean the search?