Admins should be able to see all user custom profile fields. If a custom profile field is marked as PROFILE_VISIBLE_PRIVATE, it should be visible to the user but also to admins who have moodle/user:update. Note: Admins can edit the fields but not see them without going into edit.
in user/profile/lib.php CHANGE:
return ($this->userid == $USER->id);
if ($this->userid == $USER->id) return true;
// Fall through to default which checks moodle/user:update