#!/usr/bin/perl
use 5.014;

my @arr = ( "line1 perl monks wisdom",
           "line2 monks perl wisdom",
           "line3 perl perl monks monks wisdom",
           "line4 perl perl monks monks monkly wisdom",
        );

my $matchword = qr/monks/;

for my $line (@arr) {
    if ( $line =~ $matchword ) {
        my @arr_out = split /($matchword)/, $line;
        for my $arr_element(@arr_out) {
            say $arr_element;
        }
    }
}

=head OUTPUT
line1 perl
monks
 wisdom
line2
monks
 perl wisdom
line3 perl perl
monks

monks
 wisdom
line4 perl perl
monks

monks
 monkly wisdom

=cut