The Problematic Situation:
When you add any lookup in Salesforce on a layout from one object to another, and try searching for available values, you face the below issues:
1-You can only search by record name. (main value) – Default settings
2-You need at least 2 characters to for the search to work
3-You cannot search for values in any other field, your search is limited to the main field.
4-System will only display by default recent viewed items (by you) and not all the available values.
Therefore users are expected to know all possible values of the record name field, usually a challenge for users.
The Workaround solution:
First let us go over the search tools and options that are provided by Salesforce :
1-The Wild Search (*)
Salesforce provides a wild search, *, but you need to provide along with it at least 2 characters to work.
This is a great feature, right, but not good enough to find all possible options.
2-The “All Fields” Search
This is also a great feature where you can search not only the main field, but all fields within an object.
In order to enable this options , called Enhanced Lookups, of a certain object, go to
Setup>Customize > Search > Search Settings and check the Enhanced Lookups.
You will not have a new option on the lookup search “All Fields”
3-The workaround.
If you wish to display all available value, all you need to do is create a new field on the destination object, of Type Text with default value “ALL”
You may display or hide the field from the layout, below is an example.
Note: for existing records, you will need to update this field manually(手动地) with the “All” value. While for any new record, it will automatically take the default value “All”
Solved!
Now you can do a lookup search, searching for the value “All” using the “All Fields” option.
If you wish to edit the columns to be displayed on the Lookup search Dialogs
Setup -> App Setup -> Customize -> Search Layouts.
补充：为标准对象中的lookup新增“新建”按钮，如下图：
文章转载自：http://www.salesforce-me.com/how-to-show-all-available-records-in-a-lookup-search/
相关问题：https://success.salesforce.com/answers?id=90630000000gvLoAAI