@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': $!";
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to...

open my $fh, "<", "Configs/$file" or die "Can't open '$file': $!";
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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': $!";
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