Não há atalho. Você precisa especificar cada coluna separadamente.
SELECT * FROM shoutbox
WHERE name LIKE '%$search%'
OR foo LIKE '%$search%'
OR bar LIKE '%$search%'
OR baz LIKE '%$search%'
SELECT * FROM shoutbox
WHERE name LIKE '%$search%'
OR foo LIKE '%$search%'
OR bar LIKE '%$search%'
OR baz LIKE '%$search%'