The answer given by svick is not correct. It is possible.
There's git request-pull which is part of the Git suite. Using that command line tool, you could create a pull request that could be sent per E-Mail.
Example:
your origin holds a branch master. Now you create a local bugfix branch fix, implement the bug fix and push that fix branch to origin:
git push origin fix:fix
Then, you want someone to merge the changes made in the fix branch into master. Create the pull request with
git request-pull master origin
This will create a text formatted as follows:
The following changes since commit <SHA of master>:
  <commit message of SHA of mster>
are available in the git repository at:
  <repo location> fix
<User Name> (<Number of Commits>):
      <messages of the commits>
      ...
 <changed files>
 ...
 <file statistics>
If the merge request shall go to somebody that cannot access your repo where you pushed your changes, there's always the opportunity of doing it with git format-patch.
After pushing your fix branch to origin (you don't even need to do that), while being on the fix branch create the patch using
git format-patch master..
This will create a patch file for each commit you did in fix since branching off master. You could bundle the generated .patch files with
tar czf fix.tgz *.patch
and then send to someone e.g. via E-Mail to review and apply.
For the sake of completeness: applying the patches could be done with git am.