The % sign acts as a wildcard:
C% will find Cadagon, Cudduggan, Cadwgan, Charles, Cooper etc.
Wa% will find Waters, Watters, Walters, Watkins etc.
%s will find Williams, James, Giles, Thomas, Jones etc.
C%s will find Cross, Charles Collins etc.
The _ (underscore) sign acts as any one letter:
_owell will find Howell, Powell etc
_%l will find Howel, Howell, Powel, Powell, Cecil, Blackwell