my $x = "klops";
my @orig = qw(apfel klops klops börne joghurt klops nüß);

my (@have, @havenot);

push @{(/$x/ ? \@have : \@havenot)}, $_ for @orig;

print "@have\n@havenot\n";
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If you want, you can assign @have back to @orig at the end.