Search content within a bytea field

Hi all,
I'm trying to search for some content within a bytea field. My
PreparedStatement looks like this:

SELECT id FROM mytable WHERE myfield LIKE ?

Now, when I execute a

ps.setString(1, "%" + value + "%")

where 'value' is the value I want to search for, the PS becomes

SELECT id FROM mytable WHERE myfield LIKE %VALUE%

and the query clearly fails ("operator does not exist: bytea ~~
character varying"). Now, my question is....why? What am I doing
wrong?

Thanks for you help!