write all words from string containing substring C++

Question

I need to print all words from the text file which includes substring, how can I add to the code? The code which I have is printed below

#include <iostream>
#include <fstream>
#include <bits/stdc++.h>
using namespace std;


int main()
{
   ifstream f("lab.txt");
   fstream n("lab2.txt", ios::out);
   if (f.is_open()) {
       string s;
       string word = "";
       string substring ="ab"

       while(getline(f, s)) {
           for (auto x : s)
           {
               if (x == ' '|| x==','|| x=='!'|| x=='?'|| x==':'|| x==')'|| x=='(')
               {
                   n << word << endl;
                   word = "";
               }
               else {
                   word = word + x;
               }
           }
           n << word << endl;
           word="";
       }
    }
}