# I assume the database handler $dbh is already initialized

my $sth = $dbh->prepare("
   SELECT * FROM table 
   WHERE field1 LIKE ?
   AND   field2 LIKE ?
   AND   field3 LIKE ?
   AND   field4 LIKE ?
   AND   field5 LIKE ?
");

for ($field1, $field2, $field3, $field4, $field5) {
   $_ = "" unless defined $_;
   $_ .= "%";
}

$dbh->execute($field1, $field2, $field3, $field4, $field5);

# But please choose better names than $fieldX :-)