I guess the method fetchall_arrayofhashref isn't provided for performance issues (mapping the keys to every hash at once). Anyway, knowing the columns names (as you should), you can mimic the behavior of the method you want with something like this:

my @fields = qw(name surname);
my $select = sprintf 'SELECT %s FROM clients', join(',', @fields);
my @arr_of_hashes = map {my %hash; @hash{@fields} = @$_; \%hash}
                               @{ $dbh->selectall_arrayref($select) };
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$|=$_="1g2i1u1l2i4e2n0k",map{print"\7",chop;select$,,$,,$,,$_/7}m{..}g