hi,
This is nice question.
generally we are using to search in the memcache vales through its key.

For example.

test_Key = testing

here test_key is memcache key
testing is the memcache values for the Key test_Key

to search for testing
we can do like this
if($memClient -> get('test_Key'))
echo "Search values Found";

i hope it is clear for you.

__________________
With,
J. Jeyaseelan
Everything Possible