public void MyMethod(string param)
{
    var myList = new string[] 
    {
        "example1",
        "example2",
        "example3"
    };
    foreach (var item in myList)
    {
        if (!param.Contains(item)) continue;
        //Do something here
    }
}

static int FastIndexOf(string source, string pattern) {
  if (pattern == null) throw new ArgumentNullException();
  if (pattern.Length == 0) return 0;
  if (pattern.Length == 1) return source.IndexOf(pattern[0]);
 bool found;
  int limit = source.Length - pattern.Length + 1;
  if (limit < 1) return -1;
 // Store the first 2 characters of "pattern"
  char c0 = pattern[0];
  char c1 = pattern[1];
 // Find the first occurrence of the first character
  int first = source.IndexOf(c0, 0, limit);
 while (first != -1) {
   // Check if the following character is the same like
    // the 2nd character of "pattern"
    if (source[first + 1] != c1) {
      first = source.IndexOf(c0, ++first, limit - first);
      continue;
    }
   // Check the rest of "pattern" (starting with the 3rd character)
    found = true;
    for (int j = 2; j < pattern.Length; j++)
      if (source[first + j] != pattern[j]) {
        found = false;
        break;
      }
   // If the whole word was found, return its index, otherwise try again
    if (found) return first;
    first = source.IndexOf(c0, ++first, limit - first);
  }
  return -1;
}