// Implements hook_block_view().
function customsearch_block_view($delta = '') {
  if (user_access('search content')) {
    $block['content'] = drupal_get_form('customsearch_block_form');
    return $block;
  }
}

// Implements hook_forms().
function customsearch_forms() {
  $forms['customsearch_block_form']= array(
    'callback' => 'customsearch_box',
    'callback arguments' => array('customsearch_block_form'),
  );
  return $forms;
}

// Form builder; Output a search form for the search block's search box.
function customsearch_box($form, &$form_state, $form_id) {
  $form['customsearch_form'] = array(
    '#type' => 'textfield',
    '#title' => '',
    '#title_display' => 'invisible',
    '#default_value' => '',
    '#attributes' => array(
      'title' => t('Search the website'),
      'placeholder' => t('search the website'),
    ),
  );
  $form['actions'] = array('#type' => 'actions');
  $form['actions']['submit'] = array('#type' => 'submit', '#value' => t('Search'));

  // define function to determine search destination
  $form['#submit'] = array('customsearch_search_box_form_submit');

  return $form;
}

// overide submission of search query from block
function customsearch_search_box_form_submit($form, &$form_state) {
  $searchterm = $form_state['values']['plus_search_form'];
  $search_path = 'specialcustomsearch'// replace with the path to your search results page
  // pass search term to your search results page as argument
  drupal_goto($searchpath .'/'. $searchterm);
}