The element you are trying to find is inside an iframe. So you will have to first switch to the iframe and then find the element.
You can try this :
//First switch to iframe
driver.switchTo().frame(driver.findElement(By.id("Search")));
WebElement e = driver.findElement(By.xpath("//input[@id='com.peopleclick.cp.formdata.SEARCHCRITERIA_KEYWORDS']"));
//do further stuff .... and then switch back to form
driver.switchTo().defaultContent();
Let me know if it works.