You would need to do this at the join which would require you to use a command object. I have never used LIKE in a join before as I am sure it is not efficient but it is the only way I can think of your situation working.
You command will look something like this
SELECT customer.number, customer.name, beverages.comment
FROM customer INNER JOIN
beverages ON customer.FIRSTNAME LIKE ('%' + beverages.FIRSTNAME + '%')
WHERE beverages.comment LIKE '%beer%'