my @values = qw/Otago Auckland Nortland/;

#Quote Values to be safe
my $values = 
  join("," 
       ,map { $dbh->quote($_) } @values 
      );

my $statement = "
  SELECT c_email, c_first, c_last 
    FROM tblClient, tblGroup, tblRegion 
   WHERE  tblGroup.g_name = 'motel' 
     AND tblRegion.r_name IN ( $values )";

my $sth = $dbh->prepare($statement);
$sth->execute();