I don't think MySQL has a function like that, but you can maybe try something like stripping off the s or something before doing the search...
$search_field = "Ninos";
If(substr($search_field, -1) == "s") {
$search_field_washed = substr($search_field, 0, (strlen($search_field)-1));
} else {
$search_field_washed = $search_field;
}
echo $search_field_washed;
Then use the washed variable ($search_field_washed) in your query.
select * from store where name like '%$search_field_washed%' OR name like '%$search_field%' order by name;
The trouble with this method is if the search string is something like "harrass" or "mess", because they would be truncated too, but it might be a fair trade-off. That's for you to decide. Also, it wouldn't help if a restaurant was called "D'Angelos" and the user inputted "Dangelos" or "Dangelo's".