Tente desta forma:
SELECT *
FROM test_addresses
WHERE (addr4 is not null and country like '%'||addr4||'%')
or (addr5 is not null and country like '%'||addr5||'%')
Sql Fiddle Demo
SELECT *
FROM test_addresses
WHERE (addr4 is not null and country like '%'||addr4||'%')
or (addr5 is not null and country like '%'||addr5||'%')