Such simple regexes will break on anything else but words composed of ASCII characters. Also it will add the spaces to the words.

Try using split:

use Modern::Perl;
use utf8;

while (<DATA>) {
    my @words = ($_ =~ m/[a-zA-Z0-9]+\s/g);
    say 'Regex  : ', join '*', @words;
    @words = ($_ =~ m/[a-zA-Z0-9]+\s*/g);
    say 'Regex *: ', join '*', @words;
    @words = split /[^\pL\pN]+/; # split on non letters + numbers
    say 'split:   ', join '*', @words;
}


__DATA__
This is a simple sentence.
This one has punctuation, indeed it has!
And  multiple  spaces  all  over  the  place  !
And nön-ascii chàraçtérs, wôw!
What about l33t sp33ch 4 u?
[download]

Output:

Regex  : This *is *a *simple 
Regex *: This *is *a *simple *sentence
split:   This*is*a*simple*sentence
Regex  : This *one *has *indeed *it 
Regex *: This *one *has *punctuation*indeed *it *has
split:   This*one*has*punctuation*indeed*it*has
Regex  : And *multiple *spaces *all *over *the *place 
Regex *: And  *multiple  *spaces  *all  *over  *the  *place  
split:   And*multiple*spaces*all*over*the*place
Regex  : And *ascii 
Regex *: And *n*n*ascii *ch*ra*t*rs*w*w
split:   And*nön*ascii*chàraçtérs*wôw
Regex  : What *about *l33t *sp33ch *4 
Regex *: What *about *l33t *sp33ch *4 *u
split:   What*about*l33t*sp33ch*4*u
[download]