find variations of a word in a string on python

So, I'm running Python 3.3.2, I have a string (sentence, paragraph(s)):

mystring=["walk walked walking talk talking talks talked fly flying"]

And i have another list with words i need to search in that string:

list_of_words=["walk","talk","fly"]

And my question is, is there a way to get as result:

1. The word walk or a variation is present 3 times
2. The word talk or a variation is present 4 times
3. The word fly or a variation is present 2 times

Bottom line, is it possible to get a count on all possible variations of a word?

from difflib import get_close_matches
mystring="walk walked walking talk talking talks talked fly flying"
list_of_words=["walk","talk","fly"]

sp = mystring.split()
for x in list_of_words:
    li = [y for y in get_close_matches(x,sp,cutoff=0.5) if x in y]
    print '%-7s %d in %-10s' % (x,len(li),li)

result

walk    2  in ['walk', 'walked']
talk    3  in ['talk', 'talks', 'talked']
fly     2  in ['fly', 'flying']

The cutoff refers to the same ratio as computed by SequenceMatcher :

from difflib import SequenceMatcher

sq = SequenceMatcher(None)
for x in list_of_words:
    for w in sp:
        sq.set_seqs(x,w)
        print '%-7s %-10s %f' % (x,w,sq.ratio())

result

walk    walk       1.000000
walk    walked     0.800000
walk    walking    0.727273
walk    talk       0.750000
walk    talking    0.545455
walk    talks      0.666667
walk    talked     0.600000
walk    fly        0.285714
walk    flying     0.200000
talk    walk       0.750000
talk    walked     0.600000
talk    walking    0.545455
talk    talk       1.000000
talk    talking    0.727273
talk    talks      0.888889
talk    talked     0.800000
talk    fly        0.285714
talk    flying     0.200000
fly     walk       0.285714
fly     walked     0.222222
fly     walking    0.200000
fly     talk       0.285714
fly     talking    0.200000
fly     talks      0.250000
fly     talked     0.222222
fly     fly        1.000000
fly     flying     0.666667