use Data::Dumper;

use strict;
use warnings;

my $params = "option1 = value0 value1 value2 option3 =value3 value4 option2=value5";
$params =~ s/\s*=\s*/=/g;
my @params = split /\s+/, $params;
my %params;
my $cur_val;
for my $param (@params) {
	my @pairs = split /=/, $param;
	$cur_val = $pairs[0] if ($#pairs) ;
	push @{$params{$cur_val}}, $pairs[-1];
}
print Dumper(\%params);