To specify a term which contains spaces, use single quotes like this: 'term with spaces'

By using a search like fieldname:term, you can search in the following fields:

classifiers
The trove classifiers of a package. Use single quotes to specify a classifier, as they contain spaces: classifiers:'Programming Language :: Python :: 3'
index
The name of the index. This is only the name part, without the user. For example: index:pypi
keywords
The keywords of a package.
name
The package name. For example: name:devpi-client
path
The path of the package in the form '/{user}/{index}/{name}'. For example: path:/root/pypi/devpi-server
serial
Undocumented
type
The type of text. One of project for the project name, title for the title of a documentation page, page for a documentation page, or one of the following project metadata fields: author, author_email, description, keywords, summary. For example: type:page
user
The user name.

End a term with an asterisk to search by prefix like this: path:/fschulze/*

Group query clauses with parentheses.

Use the AND, OR, ANDNOT, ANDMAYBE, and NOT
operators to further refine your search.
Write them in all capital letters, otherwise they will be interpreted as search terms.
An example search would be: devpi ANDNOT client

Boost a term by adding a circumflex followed by the boost value like this: term^2