use strict;
use warnings;
use Data::Dumper;

my $data="key1=value1 key2=value2 value3 key3=value4 value5 value6 key4=value7 key5=value8 key6=value9 value10";

# Albannach version
my %hash;
while ($data =~ /(\w+=)((\w+( |$)+)+)/g) {
  $hash{$1} = $2;
}
print Dumper \%hash;

# gumpu version:
my %foo;
while ($data =~ m/(\S+)=(\S+($|([^=]+\s+)+))/g) {
  $foo{$1}=$2;
}
print Dumper \%foo;