@files only contains the names of the files, so you need to prepend the directory path. You can change this bit:
open my $fh, "<", $file or die "Can't open '$file': $!";
to...
open my $fh, "<", "Configs/$file" or die "Can't open '$file': $!";
Update:
In light of what
GotToBTru says below, and although other ways have already been pointed out, you could add these lines:
foreach my $file (@files) {
next if $file =~ m/^\./; # skip .. and .
next unless -f "Configs/$file"; # test to see if a file
open my $fh, "<", "Configs/$file" or die "Can't open '$file': $!";