[рони]

var text = "Eugene Yevgen Oksai, Olesya, Yevgen",
      myName = "Yevgen",
      hits = [];
  for (i = 0; i < text.length; i++) {
      if (text[i] === 'Y') {
          var str = '';
          for (j = i; j < (i + myName.length); j++) {
              str += text[j]
          };
          hits.push(str)
      }
  }

  if (hits.length) alert(hits);