SELECT * FROM xy WHERE name LIKE '%german special char'

Hello,
in my postgres db i have several Tables with german Special Chars like
ÄÖÜßäöü.

I have no problem displaying them with any terminal, php, jdbc and so on,
but the like pattern doesn't find any of this special chars.

The Statement
SELECT * FROM XYZ WHERE name LIKE '%Müller%'
doesn't any of a matching row.

Is there a solution for this problem ? LIKE '%M_ller%' doesn't work, too !

I don't want to change the data in the tables, because displaying the data
is ok, but i have to search in it.

Thanks
Berger