Sounds a lot like new query features described in the PT 8.54 Release Value Proposition (optional prompts and default values for prompts). See Oracle's PeopleSoft PeopleTools 8.54 Release Value Proposition (Doc ID 1664634.1) for more information.
Within Query Manager, you could use a Like criteria with a prompt, but then you couldn't use a prompt table. For example, the DEPTID criteria would be DEPTID LIKE :1, and if the user wants all departments they enter % as the prompt value. You could also use more sophisticated criteria, such as
('Y' = :1 or DEPTID=:2)
and use something like the PSYESNO field for the :1 prompt with heading text such as "All Departments". You would need to group the criteria using brackets due to the 'or' condition. The prompt would dispay as
All Departments:  (a checkbox)
If you use a prompt table for the deptid prompt, though, the user would still have to select a valid deptid even if they checked the All Departments checkbox.
Of course, building a custom component is always an option.