this do the trick :
$newName = str_replace('example','test',$product->getName());
$product->setName($newName);
Find it and add the other attributes :
$newDescription = str_replace('example','test',$product->getDescription());
$product->setDescription($newDescription);
$newShortDescription = str_replace('example','test',$product->getShortDescription());
$product->setShortDescription($newShortDescription);
Then save each attribute like this :
$product->getResource()->saveAttribute($product,'description');
$product->getResource()->saveAttribute($product,'short_description');
Or just save the product (time and resource consuming)
$product->save();
To select only product having example in name OR description OR short_desc use this
-addAttributeToFilter(array(array('attribute'=>'name','like'=>'%example%'), array('attribute'=>'description','like'=>'%example%'),array('attribute'=>'short_description','like'=>'%example%')))
Instead of
->addAttributeToFilter('name',array('like','%example%'))