Easy.

while(<>) {
    $_ =~ s/([^ ])=/$1 =/;
    $_ =~ s/=([^ ])/= $1/;
    print;
}

The [^ ]=, which means "not space followed by equal sign". But since [^ ] will by itself eats a symbol - you will need to "preserve it" by using parenthesis, and reuse that symbol by using $1.