the easiest thing I could think is:
do you have only those 4 roles? (admin, candidate, employer and non-logged)
if yes, you could use
!current_user_can('employer')
otherwise you can always use || operator to verify multiple conditions and the function current_user_can()
!is_user_logged_in() || current_user_can('administrator') || current_user_can('candidate')
I didn’t write them since there are only 2 files and I modified both, it’s quite easy to find the function I modified.
